In the Linux kernel before 4.13.5, a local user could create keyrings for other users via keyctl commands, setting unwanted defaults or causing a denial of service.
git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=237bbd29f7a049d310d907f4b2716a7feef9abf3
www.securityfocus.com/bid/104254
bugzilla.redhat.com/show_bug.cgi?id=1580979
bugzilla.redhat.com/show_bug.cgi?id=1856774#c11
bugzilla.redhat.com/show_bug.cgi?id=1856774#c9
github.com/torvalds/linux/commit/237bbd29f7a049d310d907f4b2716a7feef9abf3
support.f5.com/csp/article/K37301725
usn.ubuntu.com/3754-1/
www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.13.5